Such a double wire former is part of a paper machine and serves substantially to dewater a fiber suspension intended for paper production which is spread out on a permeable wire surface in order to distribute or arrange the component parts contained in the suspension in a desired form. In this stage of the paper production one normally speaks of sheet forming, web forming or formation. This stage determines the quality of the subsequently produced paper to quite a substantial degree.
It has been shown in many cases that sheet forming on a curved surface between two paper machine wires brings advantages. In this case, the water is forced out of the suspension and through the wire by the wire pressure occurring as a result of the curvature and the wire tension. The dewatering can in this case be further reinforced by under-pressure. Furthermore, an influencing of the sheet forming process, for example by pressure or suction shocks is known. For the design of such a double wire former, a complex field of parameters is available which, on the one hand, leads to a large scope for influencing the paper web produced but, on the other hand, requires a high complexity of the machinery and the control equipment. Even in utilising the state of knowledge, the expert has to occasionally accept unsatisfactory results if the paper web is sensitive and if a particularly even distribution of all the web components is required.